Conventional solar battery charging systems employ a xe2x80x9cback flowxe2x80x9d or reverse current diode to prevent battery current from flowing back through a solar array in the absence of solar energy. Typically, a Schottky diode is used for this reverse current protection due to a low forward voltage drop required for Schottky diode operation. The forward voltage drop has a direct impact on charge efficiency such that the less power that is dissipated across the diode, the more charge power is delivered to the battery. The charge efficiency has been acceptable when dealing with macro solar charging systems since the battery charge voltages have been typically xe2x80x9chighxe2x80x9d in ratio to the Schottky diode forward voltage drop. However, this is not desirable in micro solar charging systems where the charge voltages are not high in ratio to the Schottky diode forward voltage drop. Therefore it would be desirable to provide a circuit that prevents battery back flow current having less forward voltage drop than a Schottky diode.
An active switch for electrically connecting and disconnecting a power source such as a solar array to a charge storage device is provided. The active switch allows a minimal amount of reverse back current flow from the charge storage device to the power source and has a low on-resistance.